A material with a low stacking fault energy (SFE) can form a twin boundary, for example, a nanoscale twin or nanotwinned (nt) boundary, when synthesized via physical vapor deposition (e.g., magnetron sputtering) or electrodeposition. The presence of nt boundaries may strengthen a material relative to a coarse-grained material. Unlike some nanocrystalline metals, nt metals may exhibit large, uniform tensile ductility.